hive-forge: dedup the --json refusal into refuse_json(), test it, cover attachment-get/artifact-get too

hive-forge/src/verbs/attachment_get.rs

@@ -14,6 +14,7 @@ use anyhow::{Result, bail};
 use clap::Args as ClapArgs;
 
 use crate::client::Client;
+use crate::verbs::refuse_json;
 
 #[derive(ClapArgs)]
 pub struct Args {
@@ -34,6 +35,11 @@ pub struct Args {
 /// the input, if the download fails (network, 4xx/5xx), or if the
 /// output path cannot be written.
 pub fn run(client: &Client, args: Args) -> Result<()> {
+    refuse_json(
+        client.json_mode(),
+        "attachment-get",
+        "it downloads the raw attachment bytes, there is no JSON form",
+    )?;
     let uuid = extract_uuid(&args.attachment)?;
     let url = client.attachment_url(&uuid);
     let bytes = client.get_bytes_raw(&url)?;